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Thread: Head Porting

  1. #1
    cbn70's Avatar
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    Head Porting

    Who are most people recomending on head porting? I have talked to some places and all they can say is "send it to us and we will make you go fast". They don't seem to ask a bunch of questions, like what are you using the bike for, or what kind of mods have you done to the motor. This does not seem to give me the warm fuzzy feeling about sending off a head to them to get some work done to it. Or am I just crazy and anyshop can do a good job of it?

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  3. #2
    Sensei 66Sprint's Avatar
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    Re: Head Porting

    Branch Flowmetrics, Team Hansen Honda, etc would be where I'd go.....
    NOT everyone know what they are doing as far as flowing a head goes, these guys do.....Expect to pay BIG DOLLARS for good work......

  4. #3
    cbn70's Avatar
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    Re: Head Porting

    When you say big dollars what are you talking about?? 100?? or 500?? Just courious as I never got a price from the people I talked to. thanks

  5. #4
    Supporting Vendor ZephyrKing's Avatar
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    Re: Head Porting

    The big question is why are you porting the heads and what do you hope to achieve in doing so? This may sound like an obvious question, but the answer is much more difficult than you might think. Porting your heads changes the dynamic of your engine, part of which is the potential to make more power and go faster. However it is always at a compromise. Without going into a long discussion about engine dynamics you need to understand the trade offs and other parts that need to support head porting. Porting the heads can increase air flow, assuming they are done correctly (sometimes porting actually hurts airflow), but typically it is at higher engine RPM's , which will affect low end performance. Ported heads need to have calibration, exhaust and cam modified to support the new airflow and to achieve the goal of the engine an the type of riding you are tying to do. If you plan on just going fast on the street, I would optimize your intake, exhaust and cam to push your stock head to its limit before attempting to have a head ported. Engine building is like making a cake, all the ingredients are important and must work together to get the best result.
    Check our our Shop's new website: www.common-motor.com. We have repair parts for CL / SL /CB350's , CL / CJ / CB360's and CL / CB450's & CB500T's (DOHC)! Questions drop me a line: Brenden@common-motor.com / 832-356-7670 (tech line)

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  6. #5
    cbn70's Avatar
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    Re: Head Porting

    Yes I understand what you are saying. This is going to be a flat track motor, with the usuall mods, cam, bigger pistons, bigger carbs. The ususal go fast stuff. Just want that little bit extra.

  7. #6
    Super Moderator outobie's Avatar
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    Re: Head Porting

    I'd add Bore-tech to the list of go to engine builders...

    who ever you choose for porting should also be consulted on for cam, carbs, pistons, exhaust so you have a complete and complimentary package as well as a single source to go to with problems.

    $3k is what it costs to build a 350 motor
    CB350 K5 - Uber Café- Engine build 3
    CL350 K4 - Cafe build done waiting on final assembly
    CB350 K0 - Full restoration w/Hondaline bags & fairing
    SL350 K2 - Bubba Shobert flat track build on deck
    CB-1 400F - unrestored mint rider
    2012 Guzzi V7 Racer - Daily Ride

  8. #7
    cbn70's Avatar
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    Re: Head Porting

    what about $$$ just for the porting? I have all the rest of the parts already. Was wanting to get the porting done some time in January, so hopefully would have it back by spring time

  9. #8
    Super Moderator outobie's Avatar
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    Re: Head Porting

    you'd have to call and ask for what you want...last time I had head work done I paid about $300 to port, add bronze guides and cut new valve seats....that was about 4 years ago. that was for a simple port cleaning and match grinding to work with the VM32 carbs...you can spend a lot more if you get your heads flowed

    what cam do you have? did you get the cam and rockers hardened together? (important for longevity)
    CB350 K5 - Uber Café- Engine build 3
    CL350 K4 - Cafe build done waiting on final assembly
    CB350 K0 - Full restoration w/Hondaline bags & fairing
    SL350 K2 - Bubba Shobert flat track build on deck
    CB-1 400F - unrestored mint rider
    2012 Guzzi V7 Racer - Daily Ride

  10. #9
    cbn70's Avatar
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    Re: Head Porting

    I have to go and check my notes but I think it is the megacycle 123-20 cam. I sent them my rockers as well then they re did them.

  11. #10
    Super Moderator outobie's Avatar
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    Re: Head Porting

    that's a great all round cam...you don't need much porting with that one...just clean up the intake... get rid of the valve guide hump open it up to mach your carb/intake boots and smooth it out.
    CB350 K5 - Uber Café- Engine build 3
    CL350 K4 - Cafe build done waiting on final assembly
    CB350 K0 - Full restoration w/Hondaline bags & fairing
    SL350 K2 - Bubba Shobert flat track build on deck
    CB-1 400F - unrestored mint rider
    2012 Guzzi V7 Racer - Daily Ride

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